Method of producing nu-chloramide vesicant protective fabric and the resulting fabric



United States Patent Ofiice 3,353,989 Patented Nov. 21, 1957 METHOD OFPRODUCING N-CHLORAMIDE VESI- CANT PROTECTIVE FABRIC AND THE RESULT- INGFABRIC Carlo G. De Marco, Cochituate, Mass, assignor to The UnitedStates of America as represented by the Secretar of the Arm No Drawing.Fiied June 16, 1964, Ser. No. 375,673

5 Claims. (Cl. 117-621) ABSTRACT OF THE DISCLQSURE A permanent vesicantprotective, resin finish for fabric materials formed by curing methylolderivatives of nitrogenous resin-forming materials in situ, said resinhaving sites which will react with hflogen ions to form N chloramides.

The invention described herein, if patented, may be manufactured andused by or for the Government for governmental purposes without thepayment to me of any royalty thereon.

This invention relates to a vesicant resistant finish for fabrics andmore particularly, a permanent resin finish for porous fabrics which canbe readily and easily converted to a vesicant vapor-resistant finish.

Personnel exposed to vesicant agents, in addition to respiratoryprotection, require some form of protective covering to shield the bodyfrom attack by these agents. While an impermeable garment would affordcomplete protection by virtue of its ability to exclude all vapors orgases, such garments are not suitable for use for other than extremelybrief periods of time because of discomfort to the wearer resulting fromthe accumulation of water vapor Within the garment. A permeable garmenthaving built-in vesicant protection would be preferred both for reasonsof comfort and because it would eliminate the need for a special purposegarment.

It is known that vesicant agents, e.g., mustard and organicohloroarsines, are inactivated by reaction with halogens. Variouscompounds containing halogens in a form suitable for reaction withvesicant agents have been applied to porous fabrics to create a barrierto vesicant vapors. Such compounds have been applied as dusts or in aliquid vehicle to the fabric and are loosely deposited on the surface ofthe fabric fibers. Attempts to increase the retention of the protectivematerials on the fabrics by use of binders have not been satisfactorybecause such materials are usually tacky in nature, have poor resistanceto laundering and, in some instances, have an adverse effect on thestrength of the fabric. Additionally, clothing containing anti-vesicanthalogen materials cannot be hot pressed without serious loss of fabricstrength, as the high temperatures involved tend to break down thehalogen containing compounds and releasing hydrochloric acid whichseverely attacks and degrades the cellulosic fibers.

It is among the objects of the present invention to provide a treatmentfor air-permeable fabric materials having at least a 50% cellulosiccontent that will prevent the passage of vapors of vesicant agentsthrough the fabric. It is a further object to provide a permanent,non-injurious resin finish for such fabric materials which can be simplyand readily reacted with a halogenating agent to form avesicant-resistant finish and which can be further treated to remove thehalogen agent from the resin finish. It is a further object to provide avesicant-resistant treatment for textile fabrics that is relativelystable, can easily be brought up to full strength, and does notadversely affect the tensile strength of the fabric.

The objects of my invention are accomplished by treating permeablefabrics, having at least a 50% cellulosic content by weight, withcertain nitrogenous resin-forming materials which are cured on thefabric to form an insoluble and permanently fixed resin finish. Thisresintreated fabric is capable of reacting with halogen ions, e.g.,chlorine ions, and holding the halogen in a labile state, capable ofreacting with and inactivating the vapors of mustard or organicchloroarsines. When the presence of the halogen is no longer required ordesired, it may be removed from the resin by rinsing the fabric in awater solution containing a reducing agent.

Textile fabrics which are suitable for treatment according to myinvention include fabrics composed of hydrophilic, fibrous, cellulosicmaterials such as cotton and rayon, and also blends of such materialsand non-cellulosic synthetic fibers containing at least 50% by weight ofthe cellulosic material, e.g., 50/50 intimate blends of nylon andcotton, 40/60 blends of polyethylene terephthalate and cotton. Whilefabrics woven of these fibers will be permeable to the passage of gasesand vapors, it is preferred that the permeability to air not exceed 20cu. ft./ minute/ sq. ft. at /2 inch of water pressure.

The nitrogenous resin-forming materials which are operable in myinvention include all of those which Will form resins having sites whichwill react with halogen ions to form N-chloramides. Included among theseare the methylol derivatives of dicyandiamide, urea, alkylsubstitutedurea and melamine, e.g., mono-, diand trimethyloldicyandiarnide, mono-,diand trimethylol ethyleneurea, mono-, diand trimethylolurea,mcthylolmelamine, etc.

The materials are incorporated in a liquid vehicle such as aqueoussolutions, suspensions, acid colloids or emulsions in amounts varyingfrom about 5% to about 25% by weight. A condensation catalyst isnormally included in the solution which serves to speed up the curingprocess. Catalysts may be of the acid or alkaline type such ascarbonates, organic amines or acid-forming catalysts, e.g., sodiumbicarbonate, glycollic acid, alkanolamine salts, and magnesium chloride.

The fabric is treated by dipping into a solution of the resin-formingmaterial followed by mechanical removal of excess liquid to effect a wetpickup of from 40 to about by wt. The impregnated material is then driedat temperatures below 250 F. The dried fabric is cured at an elevatedtemperature of from about 250 to about 350 F. for a brief period oftime, usually from about 3 to less than 10 minutes. Alternatively, theresin may be subjected to a Wet steam cure, i.e., curing in the presenceof steam at a temperature of approximately 210 F. for 45 to about 120minutes. Following the curing step the fabric is washed to removecatalyst and any unreacted materials. It is preferred that the resinadd-on should be from 10% to about 15% based on the dry weight of thefabric as this amount will not produce objectionable stiffening, loss ofstrength, or reduction of permeability of the fabric and will provide,when halogenated, excellent resistance to vesicant penetration. Thecured resin is insoluble and permanently fixed to the fabric.

Halogenation of the resin is accomplished by immersion of the resinfinished fabric in an aqueous solution containing positive halogen ions.Examples of suitable sources of halogen ions include sodium, calcium andlithium hypochlorites and sodium dichloroisocyanurate. It is preferredthat there be effected a chlorine concentration of 0.1 to 1.0 mg. ofelemental chlorine per sq. cm. of fabric.

Example I A resin-forming impregnating solution is prepared by slowlyadding 750 grams of monomethyloldicyandiamide to a water-acid mixture of250 grams of phosphoric acid and 337 grams of water (70 F.). The mixtureis heated to 100 F. at which temperature the reaction becomes exothermicand ice is added (250 grams) to keep the temperature below 110 F. Thematerial is completely dissolved in approximately 30 minutes whereuponthe solution is diluted with 915 grams of water at 70 F.

The solution is applied to cotton sateen cloth (9.0 oz.) by means of 2clips and 2 nips. After application, the fabric is dried at atemperature of 250 F. and cured at 350 F. for 3 minutes. After curing,the treated fabric is rinsed in tap water for about 3 minutes and againdried at 250 F. The treated fabric had a dry add-on of approximately 12%based on the dry weight of the cloth.

The fabric with its permanent resin finish is now in a form wherebywhenever it is desired to do so it may be converted to an anti-vesicantfinish by reaction with chlorine. The chlorination treatment is quitesimple and merely requires that the resin-treated fabric be immersed ina water solution containing positive chlorine ions. The fabric of thisexample was immersed in a water solution containing 2.5% availablechlorine for 15 minutes and then rinsed and dried. The source ofchlorine was sodium dichloroisocyanurate. After two days storage thefabric was analyzed and found to contain 0.85 mg. of elemental chlorineper sq. cm. of fabric.

Chlorine may be removed from the fabric when it is desired to do so byrinsing the fabric in a solution containing a reducing agent. The fabricwas rinsed in a 1 liter solution of water containing 2 grams of sodiumthiosulphate and then dried. The fabric was analyzed and found to befree of elemental chlorine. Rechlorination can be effected as describedabove.

Example II A monomethyloldicyandiamide and methylatedtrimethylolmelamine resin-treating solution is prepared by slowly addingwith agitation 150 gms. of monomethyloldicyandiamide to a mixture of 98gms. of phosphoric acid and 609 cc. of water (100 F.). The mixture isheld below 120 F. and agitated until a clear solution is obtained. 366gms. of methylated trimethylolmelamine is added to the solution andagitated until the solution again clears.

A 9 oz. cotton sateen fabric is padded with the resintreating solutionto about a 51% wet pick-up and dried at 200 F. The dried fabric is curedat 320 F. for 3 minutes. The resin-finished fabric is rinsed in clearwater and dried. The fabric now has a permanent resin finish which willreact with chlorine to form a vesicant protective finish. The fabric wasimmersed in a sodium hypochlorite solution containing 2.5% availablechlorine for a 30-minute period and was rinsed in water, dried andexhibited excellent resistance to the passage of mustard vapors.

Example III The impregnated fabric of Example II is alternatively curedby placing the padded fabric in an airtight container and held in thisstate for two hours at 210 F. to cure the resin. Thereafter, the fabricis dried, washed and dried. The resin finish is activated as in ExampleII and the chlorinated resin finish exhibited increased stability ofchlorine content over the dry, high temperature cure of Example II.

My invention would permit clothing to be permanently impregnated withthe disclosed resins and, when exposure to vesicant agents isthreatened, the clothing may be treated by immersion in a solutioncontaining halogen ions, preferably positive chlorine ions. Byimpregnating military clothing with the disclosed resin finish,protection can quickly be obtained in the field by means of chemicalswhich are readily available thereby doing away with the necessity ofstocking special purpose chemicals which can only be applied withdifficulty or which cannot be securely attached to the fabric. Since mytreatment permits after removal of the chlorine, garments can behot-pressed without danger of fabric disintegration.

The invention described in detail in the foregoing specification issubject to changes and modifications without departing from theprinciple or spirit thereof. The terminology used is for purposes ofdescription and not of limitation, the scope of the invention beingdefined by the claims.

I claim:

1. The method of providing an air-permeable protective fabric resistantto penetration of vesicant gases which comprises impregnating a fabrichaving at least a fibrous cellulosic content with a methylol derivativeof a nitrogenous resin-forming material capable of forming resins havingsites which will react with chlorine ions to form N-chloramides, curingthe resin-forming material on the fabric to form an insoluble resinfinish permanently fixed to the fabric and wherein the amount of resinaddon is from 10% to 15% by weight of the dry fabric, and treating theresin-finished fabric with a chlorinating agent that will react with theresin and form the N-chloramides.

2. The method of claim 1 wherein the resin-forming materials areselected from the group consisting of methylol derivatives of urea,alkyl-substituted urea, melamine and dicyandiamide.

3. The method of claim 1 wherein the resin-forming material ismonomethyloldicyandiamide.

4. The method of claim 1 wherein the cured resin is capable of combiningwith chlorine to effect a chlorine concentration of 0.1 to 1.0 mg. ofelemental chlorine per sq. cm. of fabric.

5. A fabric produced by the method of claim 1.

References Cited UNITED STATES PATENTS 2,628,174 2/1953 Stokes et al.117-621 2,659,681 11/1953 Weldon 11762.1 3,034,928 5/1962 Prichard1l7-143 'MURRAY KATZ, Primary Examiner.

WILLIAM D. MARTIN, Examiner. T. G. DAVIS, Assistant Examiner.

1. THE METHOD OF PROVIDING AN AIR-PERMEABLE PROTECTIVE FABRIC RESISTANTTO PENETRATION OF VESICANT GASES WHICH COMPRISES IMPREGNATING A FABRICHAVING AT LEAST A 50% FIBROUS CELLULOSIC CONTENT WITH A METHYLOLDERIVATIVE OF A NITROGENOUS RESIN-FORMING MATERIAL CAPABLE OF FORMINGRESINS HAVING SITES WHICH WILL REACT WITH CHLORINE IONS TO FORMN-CHLORAMIDES, CURING THE RESIN-FORMING MATERIAL ON THE FABRIC TO FORMAN INSOLUBLE RESIN FINISH PERMANENTLY FIXED TO THE FABRIC AND WHEREINTHE AMOUNT OF RESIN ADDON IS FROM 10% TO 15% BY WEIGHT OF THE DRYFABRIC, AND TREATING THE RESIN-FINISHED FABRIC WITH A CHLORINATING AGENTTHAT WILL REACT WITH THE RESIN AND FORM THE N-CHLORAMIDES.